A bartender commonly pours liquor from a bottle into a glass in which a drink is being prepared. A spout is often attached to the mouth of the bottle to dispense the liquor at a relatively constant flow rate so that a bartender can “free pour” the liquor without the need for a measuring device, such as a jigger. Even at a constant flow rate, the exact amount of liquor poured into each drink varies among different bartenders, and also varies from drink to drink poured by the same bartender. Variables such as “pouring angle” (angle of a bottle relative to vertical when dispensing its contents); the volume of liquor remaining in a bottle; and the temperature of the liquor, can each be a factor in the attempt to achieve a constant flow rate. These variables can affect the profits derived from a given bottle of liquor; as well as affecting the taste, and as such the quality, of a mixed drink. In addition, simple bottle spouts do not provide a mechanism to ensure that each drink dispensed from a bottle is properly accounted for. Thus, a bartender may provide free or generous drinks to friends and preferred customers without accounting to the tavern management. In response to these conditions, taverns and restaurants have installed systems for dispensing liquor to provide some accountability, although such prior systems include numerous limitations that discourage their implementation, functional usage, and accuracy.